Surround Sound Echo Xbox 360

I am having a problem with my surround sound that just started. Right now my Xbox 360 is connected to my surround sound and it used to run fine but all of a sudden I am hearing an echo from the voices in the games.

My setup is as follows – the Xbox 360 is connected to my TV with the composite cable that came with it for audio and video (the five colours, the yellow one that is associated with the three color RCA connection isn’t connected because there is no spot on my TV’s composite connection for it). The audio then goes from my television through an optical connection to an A/V switch which is then connected again by optical connection to my surround sound receiver, a Panasonic SA-PT480 which is also a DVD player (the DVD player is connected to my TV through HDMI. I use the A/V switch to control audio only because the receiver has only one optical audio input and I have multiple sources I want plugged into my surround sound (Cable, Blu-Ray, Computer, Gaming consoles etc.)

As I said the problem is that there is all of a sudden a pronounced echo coming from the voices of the games whereas about 24 hours ago the voices came through normally.